RU2749813C2 - Methods for separation of pyrolysis oils - Google Patents

Abstract

FIELD: oil industry.SUBSTANCE: invention relates to a method for treating pyrolysis oil for separating commercially desirable fractions from fractions suitable for use as a liquid fuel. The preferred starting material is derived from car tires. The method includes the first separation of the pyrolysis oil into a lighter fraction and a heavier fraction using thin-film distillation. The lighter fraction is subjected to fractional distillation. Sulfur and nitrogen are removed from the heavy fraction. Fractional distillation is carried out in steps. In the first step, the lower fraction is collected at a vacuum of 100-400 torr. The second step is carried out at a higher vacuum than the specified first step.EFFECT: efficient separation of pyrolysis oil into fractions that have an increased commercial quality and a consumer fraction, which provides a commercial fuel product with a more acceptable flash point and less volatile compounds than pyrolysis oil taken as a whole, carrying out separation without undesirable cracking reactions and coking.23 cl, 6 dwg, 2 tbl, 1 ex

Description

Background of the invention

1. The field of technology to which the invention relates

The present invention relates to methods for extracting an improved distillation feed from pyrolysis oil, more specifically, it relates to methods for performing an initial separation that results in a lighter fraction and a heavier fraction. The lighter fraction is subjected to fractional distillation, and sulfur and nitrogen compounds are removed from the heavier fraction to facilitate the use of the heavier fraction as a heavy fuel. The preferred starting material is derived from car tires.

2. Description of the prior art

As is known, rubber, for example worn tires, is pyrolyzed in a manner yielding a solid fraction such as soot, liquid hydrocarbon and gas. A liquid hydrocarbon can potentially be used as a liquid fuel. See US patents US 6833485, US 6835861 and US 7341646.

US Pat. No. 6,673,236 describes the reduction of sulfur in middle petroleum distillates by catalytic oxidation in the presence of vanadium. Pyrolysis oil is not described in this document. Ethanol is present and some of it is reported to be oxidized to form peracetic acid, which is said to promote further oxidation. The final separation is specific to the alcohols MeOH and EtOH.

US Pat. No. 8,043,495 describes the reduction of sulfur in a hydrocarbon stream using a catalytic distillation reactor and a hydrodesulfurization catalyst. It is indicated that a product is obtained with a low mercaptan content.

US Pat. No. 4,983,278 describes a two-temperature pyrolysis process that uses oil recirculation. This two-temperature process discloses that a light oil, a heavy oil and a solid residue are obtained.

US Pat. No. 3,702,292 describes the distillation of crude oil to produce a series of cuts and the subsequent catalytic cracking of the gas oil fraction to produce propane and other cuts.

US Pat. No. 8,293,952 describes a pyrolysis process using an alkali metal oxide catalyst and states that the resulting pyrolysis product has a high alcohol content.

US Pat. No. 6,444,118 describes catalytic distillation techniques used to reduce the sulfur content of naphtha streams. A distillation column reactor is used to treat oil streams containing organic sulfur and hydrogen, which are contacted in the presence of a hydrodesulfurizing catalytic distillation structure.

It is generally accepted that pyrolysis oil obtained from tires contains the valuable terpene and other unsaturated compounds, as well as mercaptans and other sulfur-containing compounds. Attempts to separate fractions containing these compounds into an economically promising fraction were unsuccessful.

Oil obtained by pyrolysis, in particular, obtained as a result of polymer pyrolysis, is a complex mixture of saturated and unsaturated hydrocarbons and includes polar compounds containing sulfur, nitrogen and oxygen. Depending on the polymer, it can also contain halogenated compounds. These oils are often marketed as low grade fuels with low profitability. Due to the moderate sulfur content of these oils, they are typically used in less harmful environmental operations or in operations where emissions are treated to remove sulfur. In the petrochemical industry, hydrodesulfurization is commonly used using a metal catalyst and hydrogen gas to convert organosulfur compounds to hydrogen sulfide plus a saturated hydrocarbon by the following reaction RSH + H ₂ → R + H ₂ S, where R is hydrocarbon. Hydrogen sulfide is converted to elemental sulfur or sulfate. This method requires the use of pressurized hydrogen gas and is usually only economically viable on a large scale.

It is generally accepted that pyrolysis oil obtained from tires contains the valuable terpene and other unsaturated compounds, as well as mercaptans and other sulfur-containing compounds. However, attempts to isolate fractions containing these compounds have not yielded commercially valuable fractions. This is due to the many problems associated with the complex nature of tire-derived pyrolysis oil. Attempts at direct distillation of pyrolysis oils lead to complex mixtures of compounds and instability of the distillate during distillation. Changing the temperature in the heating tank causes the fractions to have a wide boiling range. More importantly, pyrolysis oils provide a reactive compound that, at the high wall temperatures required for standard distillation, will react or crack during distillation, resulting in foaming and difficult control of temperature, pressure, and separation. M. Stanciulescu, M. Ikura, "Limonene Ethers from Tire Pyrolysis Oil Part 1: Batch Experiments", J. Anal. Applied Pyrolysis 75, pp 217-225, 2006, notes that limonene elutes with naphtha and suggests reacting limonene with methanol to shift its boiling point to separate it from the oil. They then need to be reacted with an ester again to extract limonene. Roy et. al . (Production of dl-limonene by vacuum pyrolysis of used tires, Journal of Analytical and Applied Pyrolysis 57 pp. 91-107, 2001) found that pyrolytic cleavage products of limonene plus thiophene and other sulfur compounds eluted with limonene make it difficult to isolate pure limonene. This demonstrates once again the difficulty of extracting limonene from pyrolysis oil.

Thus, there remains a real and substantial need for methods for treating pyrolysis oil to effect separation of commercially desirable fractions from fractions suitable for use as fuel oils.

The essence of the invention

The present invention has overcome the disadvantages of the above-mentioned prior art by providing efficient methods for treating pyrolysis vapors to separate commercially attractive fractions from heavier fractions suitable for use as liquid fuels. More specifically, in a preferred embodiment, the first pyrolysis gas separation step produces a lighter fraction and a heavier fraction. This is followed by a second stage in which the lighter fraction is subjected to fractional distillation to separate commercially attractive products. The heavier fraction in the third stage is subjected to oxidative desulfurization with nitrogen-containing organic compounds, which are removed from the desulfurization process, in order to obtain effective fuels and lubricants. The preferred initial separation of the pyrolysis oil involves thin film distillation as it effectively and economically results in the desired first separation step. Several preferred parameters with respect to the fractional distillation process are described as preferred features.

Depending on the specific objectives of a particular application, it is possible to use successfully combinations of a three-step method, including not all of these three steps.

In another embodiment, the thin film distillation is followed by a composite distillation without the use of a desulfurization step.

In a further embodiment, the thin film distillation product is subjected to oxidative catalytic desulfurization without using a fractional distillation process.

One object of the present invention is to provide efficient and effective methods for separating pyrolysis oil into (a) fractions that are of improved commercial quality and (b) a consumer fraction that provides a marketable fuel product.

It is a further object of the present invention to provide methods that can be applied at both small and moderate scale and very large scale.

Another object of the present invention is the efficient use of thin film distillation.

It is an object of the present invention to separate the pyrolysis oil into commercially attractive improved distillation feedstocks and provide a heavy fraction with a more acceptable flash point and fewer volatiles than pyrolysis oil taken as a whole.

It is another object of the present invention that, due to thin film distillation, the pyrolysis oil is subjected to a significantly lower temperature and for a shorter time than required for bulk distillation in order to achieve the desired separation without undesirable cracking and coking reactions occurring.

Another object of the invention is to provide methods for reducing sulfur and nitrogen content by catalytic oxidation.

These and other objects of the invention will become clearer from the following detailed description of the invention with reference to the accompanying drawings.

According to the claims, a method for processing pyrolysis oil is claimed, comprising

- implementation of the first separation of the specified pyrolysis oil into a lighter fraction and a heavier fraction,

- the use of thin-film distillation in the implementation of the specified first separation,

- fractional distillation of the specified lighter fraction,

- removal of sulfur and nitrogen from the specified heavy fraction,

moreover, the specified fractional distillation is carried out in stages, and

- at the specified first stage, the lower fraction is collected at a vacuum of 100-400 torr, and

- the second stage is carried out at a higher vacuum than the specified first stage.

Preferably, the method comprises the use of 10-30 trays in said fractional distillation.

Preferably, the method comprises carrying out said fractional distillation in a column containing a head reflux regulator.

Preferably, the method comprises performing said fractional distillation with said head reflux regulator set to a ratio of 2: 1 to 10: 1.

Preferably, the method comprises performing said fractional distillation to separate at least one material selected from the group consisting of mercaptans, cycloensens and a fraction of alkylated mononuclear aromatic compounds.

Preferably, the method comprises carrying out said removal of sulfur and nitrogen from the heavy fraction by catalytic oxidation using hydrogen peroxide.

Preferably, the method comprises - performing said sulfur and nitrogen removal using a catalyst that is a mixture of aluminum and molybdenum, and

- the reaction of the specified mixture at a temperature of 50-75 ° C.

preferably said catalyst is a mixture of alumina and molybdenum trioxide.

preferably, the ratio of said molybdenum trioxide to said alumina is from 0.5: 1 to 1: 0.5 in terms of weight to weight.

preferably, said lighter fraction, after fractional distillation, is subjected to catalytic oxidation using hydrogen peroxide.

preferably, said heavy fraction is suitable for use as a liquid fuel.

Preferably, the process uses said oil wherein said lighter fraction comprises 20-35 wt% of said pyrolysis oil and said heavy fraction comprises about 65-80 wt% of said pyrolysis oil.

preferably the source of said pyrolysis oil is from worn tires.

preferably said lighter fraction contains at least one material selected from the group consisting of mercaptans and cyclohexenes.

Also, according to the claims, a method for treating pyrolysis oil is claimed, comprising

- implementation of the first separation of the specified pyrolysis oil into a lighter fraction and a heavy fraction,

- the use of the specified oil, in which the separated light fraction is 20-35 wt.% of the specified oil, and the separated heavy fraction is 65-80 wt.% of the specified pyrolysis oil,

- the use of thin-film distillation in the implementation of the specified first separation,

- fractional distillation of the specified lighter fraction,

using 10-30 plates on said fractional distillation, and

- the implementation of the specified thin-film distillation in a vacuum of 100-400 torr.

Preferably, said heavy fraction is useful as a liquid fuel.

Preferably, the source of said pyrolysis oil is from worn tires.

Preferably, said lighter fraction contains at least one material selected from the group consisting of mercaptans and cyclogensenes.

Preferably, the removal of sulfur and nitrogen from said heavy fraction comprises mixing the heavy fraction with hydrogen peroxide at 50-75 ° C for about 1.5-3 hours,

carrying out the specified fractional distillation in a column containing a head reflux regulator.

It is preferable to use said thin-film distillation in a vacuum of 100-300 torr at a reactor wall temperature of 125-145 ° C.

Preferably, said heavy fraction is useful as a liquid fuel.

Preferably an oil is used in which said lighter fraction is 20-35 wt% of said oil and said heavy fraction is 65-80 wt% of said pyrolysis oil.

Preferably, the source of said pyrolysis oil is from worn tires.

Brief Description of Drawings

Figure 1 schematically shows an embodiment of the invention using a three-step method.

Figure 2 shows a schematic diagram of an apparatus applicable to stage I of thin film distillation.

Figure 3 shows a schematic diagram of an apparatus applicable in stage II of a distillation plant.

Figure 4 shows a schematic diagram of a device applicable to stage III of the desulfurization process.

Figure 5 shows a block diagram of a process according to the invention using steps I and II.

Figure 6 shows a block diagram of an embodiment of the invention using steps I and III.

Description of embodiments

According to figure 1, stage I provides an initial separation of the pyrolysis oil, preferably by thin film distillation.

The initial separation results in (a) a light cut that contains most of the commercially valuable compounds, including but not limited to terpenes, mercaptans and cyclohexenes, and (b) a heavy cut.

In stage II, the lighter fraction obtained in stage I passes through a fractional distillation system with separated reflux, whereby commercially valuable components of the pyrolysis oil are recovered from the light fraction.

Stage III receives a liquid fuel fraction, which undergoes catalytic oxidation to reduce the sulfur and nitrogen content in the heavy phase. The preferred catalyst uses molybdenum and aluminum, with the preferred catalyst being a mixture of molybdenum trioxide and alumina. It is preferred that the weight ratio of molybdenum trioxide to alumina in the mixture is from 0.5: 1 to 1: 0.5, with the most preferred ratio being about 1: 1.

Figure 2 shows the preferred thin film distillation process and equipment used with it. The motor 10 is operatively connected and drives a rotary mixer 11 with a shaft rigidly mounted thereon to rotate a plurality of scrapers 12. A surrounding heating jacket 13 is provided. The pyrolysis oil to be treated in this way is introduced through the inlet 18 and the mixer 11 is rotated by the motor 10. creating a thin layer of oil on the inner surface of the reactor jacket 13. The drive speed is set so as not to create merging channels along the inner wall of the reactor 13. The system is preferably operated in a vacuum of about 100-300 torr, most preferably at about 145-155 torr for the entire cycle while maintaining a reactor wall temperature of about 125 ° C-145 ° C, most preferably about 130 ° C-140 ° C. As a result of this process, two fractions are formed. The light fraction exits through the light fraction outlet 14. It is a fraction of the distillate enriched with essential oils and a highly volatile chemical solvent compound, forming an improved raw material for further processing. The heavy fraction exits through the lower heavy fraction outlet 16 and is a stable liquid fuel with potential value as heating feedstock and motor fuel. Any configuration of a thin-film or flow-through evaporator can be used: horizontal, vertical, co-current, or counter-current, provided that this operation is applied within the temperature and pressure ranges disclosed herein. The system preferably operates at a vacuum of about 100-300 torr, more preferably about 135-155 torr for the entire cycle while maintaining the inner wall temperature of the reactor jacket 13 at about 125 ° C-145 ° C, more preferably about 130 ° C-140 ° C ...

The advantage of thin film distillation is that the thin oil film heats up quickly and evenly and prevents interaction between lighter and heavier compounds without cracking or coking reactions. Therefore, it is preferable to use thin-film distillation to obtain improved feedstock without compromising the integrity of the heavy or light fraction of the oil.

Figure 3 shows an apparatus useful in a distillation unit in stage II for distilling the lighter fraction obtained in stage I. Figure 3 shows a head reflux regulator 20 which is operatively connected to the purified distillate fractions 20 and the distillation column 24. The column preferably contains about 10 -30 trays, most preferably about 15-20 trays. A high pressure feeder 26 is used to heat the feed material. The vaporized feed enters a multi-pass tray column 24 with a head reflux regulator 20 preferably set to a ratio of from about 2: 1 to 10: 1, most preferably from about 5: 1 to 7: 1. The distillate discharged is collected at outlet 22.

The separated fraction of commercially attractive components is typically about 20-35 wt% of the pyrolysis oil feed and the heavy fraction is about 65-80 wt% of the pyrolysis oil feed.

Example

Consider one example of Stage II. The feed material is the lighter fraction coming from the stage I of the thin film distillation.

The system is initially set to a vacuum in the range of 100-400 torr, with a preferred vacuum of about 300 torr, to collect the bottoms which are collected at about 20 ° C-25 ° C until the distillate reaches 134 ° C-145 ° C more preferably 139 ° C-141 ° C. This bottoms can be divided into several strands with different boiling ranges. An example is shown in Table 1.

Table 1

T-ra / pressure Temperature (° C) Preferred temperature (° C) Vacuum
(torr) shoulder strap 1 start - 115 ° C beginning - 105.8 300 shoulder strap 2 106 ° C-138 ° C 300 shoulder strap 3 139 ° C-141 ° C 300

The described shoulder straps consist of several low-boiling, highly volatile solvent chemicals. This includes, without limitation, xylene, toluene and styrene taken separately, as well as combined solutions that are extremely valuable in the industrial market.

After collecting the fractions to 141 ° C. under a preferred vacuum of 300 torr, the temperature is lowered to room temperature and the vacuum is increased to a range of 100-300 torr with a preferably set value of 150 torr. The cutoff is performed at 115 ° C-125 ° C, more preferably at 119 ° C-123 ° C under preferred vacuum conditions, and the cut is either added to the previous bottoms or stored separately as a solution of a lower volatility solvent. The next strand is collected, continuing to apply heat until it reaches 124 ° C-127 ° C, more preferably 125 ° C-126 ° C. Under the preferred vacuum conditions, this cut will contain the bulk of limonene and p-cymene and will be collected as a single cut and stored separately. Thereafter, a single cut is collected up to 132 ° C as a complete cutoff, ensuring that all of the high value material is extracted in this process. A general description for separation under preferred conditions is given in Table 2.

table 2

T-ra / pressure Temperature (° C) Preferred temperature (° C) Vacuum
(torr) shoulder strap 4 20-121.2 150 shoulder strap 5 118 ° C-128 ° C 121.3-122 150 shoulder strap 6 122-131.5 150

The resulting fractions can be combined or kept separately to obtain fractions containing highly volatile solvent chemicals and / or essential oils of varying purities.

FIG. 4 shows a schematic diagram of a device that can be used with part of step III of the method. Stage III is the catalytic desulfurization of sulfur-containing fractions by an oxidative process; it can also be used to remove nitrogen. Hydrogen peroxide or other oxidizing agent is introduced via line 28, and the solid catalyst, which is preferably a molybdenum / aluminum catalyst and which may be a mixture of molybdenum trioxide and alumina, is introduced via line 30. The heavy fraction from stage I is introduced via line 32 to the desulfurization process and removing nitrogen. The paddle stirrer 36 rotates under the action of the motor 34. The temperature in the reactor 40 is controlled by adding a hot or cold coolant to the jacket 42.

After the heavy fraction is introduced through line 30, a strong oxidizing agent such as hydrogen peroxide or other oxidizing agent is slowly added through inlet 28 and agitator 36 serves to stir the material. Stirring is preferably carried out at a temperature of about 50 ° C-75 ° C for about 1.5-3 hours. Upon completion of the reaction, the mixture is pumped or fed by gravity through an outlet line 44 which can transport solid aqueous and organic material to an oil / water separator 46 which can preferably be a centrifugal separator. The treated fraction, from which sulfur and nitrogen have been removed, exits outlet 50 where liquid layers are separated, and the aqueous layer containing most of the spent oxidant and catalyst is separated from the organic layer for regeneration and reuse.

The catalyst, which is preferably a mixture of molybdenum trioxide and alumina, is preferably present in a weight ratio of said two oxides from 0.5: 1 to 1: 0.5, most preferably in a 1: 1 ratio. The catalyst is added to reactor 40 with a strong oxidant which may contain about 15% by volume hydrogen peroxide together with a fraction containing sulfur and nitrogen. Stirrer 36 maintains the mixture in suspension by rotating at 700 rpm, or at a level sufficient to ensure uniform mixing of the reactants. The mixture reacts in a mild temperature range of about 50 ° C-75 ° C, preferably about 55 ° C-65 ° C due to the control of the heating / cooling jacket 42. After a reaction period of about one and a half to about 3 hours, preferably about 3 / 4 hours to 1¼ hours, the mixture is fed to an oil / water separator 46, where the liquid layers are separated from the spent oxidant and the catalyst is separated from the organic layer for regeneration and reuse.

It should be understood that in the method shown and described in connection with FIG. 1, all three stages described herein can be used. However, other combinations can be used with success. In each of the options, stage I is applied to provide suitable feedstock for further processing. In some cases, stage I can be used with stage II (FIG. 5) or stage III (FIG. 6) without using stage III in the embodiment shown in FIG. 5, and without using stage II in the embodiment of FIG. 6.

In Figure 5, stage I (60) is used to effect the initial separation and obtain a lighter fraction containing the valuable product, followed by reflux stage II (62) to effect the desired further separation and obtain marketable products.

Referring to Figure 6, Stage I is applied with Stage III (68), providing oxidative catalytic desulfurization and removal of nitrogen compounds.

An aluminum / molybdenum catalyst system used with an oxidizing agent converts organosulfur compounds to sulfate and converts nitrogen-containing organic compounds to nitrates and removes them from the oil.

The above particular embodiments of the invention have been described for purposes of illustration, however, those skilled in the art will appreciate that many changes can be made in detail without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (40)

1. A method of processing pyrolysis oil, including - implementation of the first separation of the specified pyrolysis oil into a lighter fraction and a heavier fraction, - the use of thin-film distillation in the implementation of the specified first separation, - fractional distillation of the specified lighter fraction, - removal of sulfur and nitrogen from the specified heavy fraction, moreover, the specified fractional distillation is carried out in stages, and - at the specified first stage, the lower fraction is collected at a vacuum of 100-400 torr, and - the second stage is carried out at a higher vacuum than the specified first stage. 2. A method according to claim 1, comprising the use of 10-30 trays in said fractional distillation. 3. A method according to claim 2, comprising carrying out said fractional distillation in a column containing a head reflux regulator. 4. The method of claim 3, comprising performing said fractional distillation with said head reflux regulator set to a ratio of 2: 1 to 10: 1. 5. A method according to claim 3, comprising performing said fractional distillation to separate at least one material selected from the group consisting of mercaptans, cycloensens and a fraction of alkylated mononuclear aromatic compounds. 6. The method according to claim 1, including the implementation of the specified removal of sulfur and nitrogen from the heavy fraction by catalytic oxidation using hydrogen peroxide. 7. The method according to claim 6, including - carrying out the specified removal of sulfur and nitrogen using a catalyst that is a mixture of aluminum and molybdenum, and - the reaction of the specified mixture at a temperature of 50-75 ° C. 8. The method of claim 6, wherein said catalyst is a mixture of alumina and molybdenum trioxide. 9. The method of claim 8, wherein the ratio of said molybdenum trioxide to said alumina is from 0.5: 1 to 1: 0.5 on a weight-to-weight basis. 10. A process according to claim 1, wherein said lighter fraction after fractional distillation is subjected to catalytic oxidation using hydrogen peroxide. 11. The method of claim 10, wherein said heavy fraction is suitable for use as a liquid fuel. 12. The method of claim 1, wherein said oil is used, wherein said lighter fraction is 20-35 wt% of said pyrolysis oil and said heavy fraction is about 65-80 wt% of said pyrolysis oil. 13. The method of claim 10, wherein said pyrolysis oil comes from worn tires. 14. The method of claim 10, wherein said lighter fraction contains at least one material selected from the group consisting of mercaptans and cyclohexenes. 15. A method for processing pyrolysis oil, including - implementation of the first separation of the specified pyrolysis oil into a lighter fraction and a heavy fraction, - the use of the specified oil, in which the separated light fraction is 20-35 wt.% of the specified oil, and the separated heavy fraction is 65-80 wt.% of the specified pyrolysis oil, - the use of thin-film distillation in the implementation of the specified first separation, - fractional distillation of the specified lighter fraction, using 10-30 plates on said fractional distillation, and - the implementation of the specified thin-film distillation in a vacuum of 100-400 torr. 16. The method of claim 15, wherein said heavy fraction is useful as a liquid fuel. 17. The method of claim 15, wherein the source of said pyrolysis oil is worn tires. 18. A method according to claim 15, wherein said lighter fraction contains at least one material selected from the group consisting of mercaptans and cycloensens. 19. The method according to claim 1, wherein the removal of sulfur and nitrogen from said heavy fraction comprises mixing the heavy fraction with hydrogen peroxide at 50-75 ° C for 1.5-3 hours, carrying out the specified fractional distillation in a column containing a head reflux regulator. 20. The method according to claim 19, including the use of said thin-film distillation in a vacuum of 100-300 torr at a reactor wall temperature of 125-145 ° C. 21. The method of claim 20, wherein said heavy fraction is useful as a liquid fuel. 22. The method of claim 20, wherein an oil is used, wherein said lighter fraction is 20-35 wt% of said oil, and said heavy fraction is 65-80 wt% of said pyrolysis oil. 23. The method of claim 20, wherein the source of said pyrolysis oil is worn tires.

Images